The Aero Spacelines B377SGT Super Guppy was at Dryden in May, 1976 to ferry the X-24 and HL-10 lifting bodies from the Center to the Air Force Museum at Wright-Patterson Air Force Base, Ohio. The oversized cargo aircraft is a further modification of the B377PG Pregnant Guppy, which was built to transport outsized cargo for NASA's Apollo program, primarily to carry portions of the Saturn 5 rockets from the manufacturer to Cape Canaveral. The original Guppy modification incorporated the wings, engines, lower fuselage and tail from a Boeing 377 Stratocruiser with a huge upper fuselage more than 20 feet in diameter. The Super Guppy further expanded the fuselage, replaced the original piston engines with more powerful turbo-prop engines, and added a taller vertical tail for better lateral stability. The Super Guppy and the Super Guppy Turbine are still in occasional use by NASA and Airbus Industries to transport oversize structures.

The X-24 was one of a group of lifting bodies flown by the NASA Flight Research Center (now Dryden Flight Research Center), Edwards, California, in a joint program with the U.S. Air Force at Edwards Air Force Base from 1963 to 1975. The lifting bodies were used to demonstrate the ability of pilots to maneuver and safely land wingless vehicles designed to fly back to Earth from space and be landed like an airplane at a predetermined site.

Lifting bodies’ aerodynamic lift, essential to flight in the atmosphere, was obtained from their shape. The addition of fins and control surfaces allowed the pilots to stabilize and control the vehicles and regulate their flight paths.

Built by Martin Aircraft Company, Maryland, for the U.S. Air Force, the X-24A was a bulbous vehicle shaped like a teardrop with three vertical fins at the rear for directional control. It weighed 6,270 pounds, was 24.5 feet long and 11.5 feet wide (measuring just the fuselage, not the distance between the tips of the outboard fins). Its first unpowered glide flight was on April 17, 1969, with Air Force Maj. Jerauld Gentry at the controls. Gentry also piloted its first powered flight on March 19, 1970.

The X-24A was flown 28 times in the program that, like the HL-10, validated the concept that a Space Shuttle vehicle could be landed unpowered. The fastest speed achieved by the X-24A was 1,036 miles per hour (mph--Mach 1.6). Its maximum altitude was 71,400 feet. It was powered by an XLR-11 rocket engine with a maximum theoretical vacuum thrust of 8,480 pounds.

The X-24A was later modified into the X-24B. The bulbous shape of the X-24A was converted into a "flying flatiron" shape with a rounded top, flat bottom, and double delta platform that ended in a pointed nose. The X-24B demonstrated that accurate unpowered reentry vehicle landings were operationally feasible. Top speed achieved by the X-24B was 1,164 mph and the highest altitude it reached was 74,130 feet. The vehicle is on display at the Air Force Museum, Wright-Patterson Air Force Base, Ohio. The pilot on the last powered flight of the X-24B was Bill Dana, who also flew the last X-15 flight about seven years earlier.

The X-24A shape was later borrowed for the X-38 Crew Return Vehicle (CRV) technology demonstrator for the International Space Station. The X-24B is on public display at the Air Force Museum, Wright-Patterson AFB, Ohio.

The HL-10 was delivered to the FRC by Northrop in January 1966. Its first flight was on Dec. 22 of the same year. The pilot was Bruce Peterson. The HL-10 was flown 37 times and it set several program records. On Feb. 18, 1970, Air Force test pilot Maj. Peter Hoag flew it to 1,228 mph (Mach 1.86), fastest speed of any of the lifting bodies. Nine days later, NASA's Bill Dana flew the HL-10 to 90,303 feet, the highest altitude reached by any of the lifting body vehicles. The HL-10 was also the first lifting body to fly supersonically--on May 9, 1969, with Manke at the controls.

The HL-10 featured a flat bottom and rounded top -- much like an airfoil -- and it had a delta planform. In its final configuration, three vertical fins, two of them canted outwards from the body and a tall center fin, gave the craft directional control. A flush canopy blended into the smooth rounded nose.

It was about 21 feet long, with a span of 13.6 feet. Its glide-flight weight was 6,473 lbs. and its maximum gross weight was over 10,000 lbs.

Flights with the HL-10 contributed substantially to the decision to design the space shuttles without air-breathing engines that would have been used for landings. Its final flight was on July 17, 1970.

The HL-10 is now on public display at Dryden.

X-24A; X-24B; Martin Aircraft Company; lifting bodies; Maj. Jerauld Gentry; NASA Flight Research Center; U.S. Air Force; Air Force Museum; Wright-Patterson Air Force Base; Space Shuttle; X-38; International Space Station; X-15; Bill Dana; Guppy; Super Guppy.